Hoisting apparatus.



PATENTED JAN. 22, 1907.

0. W. HUNT. HOISTING APPARATUS.

APPLIOATION FILED JULY 24,-1906.

Inventor: b m flmaiww M y W CHARLES WALLACE HUNT, OF NEW YORK, N. Y.

HOI STING APPARATUS.

Specification of Letters Patent.

Patented Jan. 22, 1907.

Application filed July 24,1906. Serial No. 327.487.

T aZZ whom it may concern.-

Be it known that I, CHARLES WALLAOE HUNT, a citizen of the United States, residing:

at West New Brighton, borough of Richmond, of the city of New York, State of New York, have invented certain new and useful Improvements in Hoisting Apparatus, of which the following is a specification, reference being had to the accompanying drawings, forming a part hereof.

This invention refers to coal and ore elevators and other forms of hoisting apparatus I in which the hoisting-drum is driven by an electric motor. The greatest difiiculty experienced hitherto in the use of hoisting apparatus of this character has been in the control of the. descent of the load.

It is the objectof this invention to make it practicable to employ the resistance offered y the running of the motor backwardas a generator, for exampleas a resistance to the descent of the load without liability to the undesirable results heretofore experienced, and this is accomplished by combining in op-' enation a mechanical brake and the electric brake above referred to the former operating tohold the load in a state of rest and being released as the latter is brou ht into operation. The mechanical brake is progressively released as resistance of the motor is progressively ,increased until the mechanical brakeis entirely released and the descent of the load is wholly controlled by the resistance of the motor.

The invention will be more fully explained hereinafter with reference to the accompa- .nying drawings, in which a practical embodiment of the invention is illustrated.

In the drawings, Figure 1 is a view in elevation, partly broken out, illustrating a hoisting apparatus equipped with the present mprovements. Fig. 2 is a diagrammatic VIGW illustrating particularly .suitable electrical connections. Fig. 3 is a detail view illustrating the application of a divided motor-field.

It will be obvious as this explanation proceeds that the invention is capable of application to anyform of hoisting or other equivalent apparatus and that a single illustratlon of the application of the invention has been chosen as a convenient and practical embodiment of the invention, sufiicient for a complete understanding of the nature of the invention.

In the apparatus shown in Fig. 1 the load (represented by a bucket a, whether full or by a weight 11, acting in empty) is shown as connected by a hoistingsheaves c, with a hoisting-drum d, which in this instance is shown as mounted directly upon the armatureshaft of a suitable electric motor f. A controller (represented gen erally at g in Fig. 1) is provided for the mo tor, and a mechanical brake 7t (shown also in Fig. 2) is provided for the drum (1, the brake in this instance being represented as applied opposition to a solenoid k, by means of'which, through suitable connections, as hereinafter described, the brakeis released.

Current is supplied to the motor from any suitable source. Assuming that it enters at Z, it is conducted to the movable contact m thence through a variable resistance n and connections n n to the field o and brushes 0 and o of the motor f. At the same time cur rent is conducted inthe arrangement shown byv the arm m, contact 2) and connections p and p to the solenoid is and thence byconnection back to the line Z.

Any suitable arrangement of connections for hoisting and for releasing the brake while hoisting maybe employed, this descri tion being more particularly concerned wit the operation of the motor during the lowering of the load.

As stated hereinbefore, the line Z is connected to the movable contact m of the controller g, and when the parts are in normal position and the load is at rest the movable contact of the controller is in-such position as to open all circuits and leave the brake h to be applied to the drum (1 by the weight 71 or Whatever other device may be employed in its place. There are provided, however, in addition to. the variable resistance 1/ two trolled, respectively, by the arms. m and m 20;" the movable contact. The resistance q is higher than the resistance a and is so formed that there is always in series with the motor a sufiicient resistance to permit the motor being drivenbackward by the minimum load at the desired speed. The resistance g is comiected to the field 0 through the connecvariable resistances gand 1', which are contion a, and the resistance 7' is connected to thesolenoid 70 through the connections r and p In describing the operation of the apparatus during the lowering of the load it will be assumed, first, that the load is in a state of rest, with the partsas represented in the! drawings, the drum (l being held from rota- 1 tion by the mechanical brake h, operated by the weight i or some other suitable means. If it be desired now to permit the read to descend, the. movable contact or M is shifted so as to close the circuit through the resistances Q and r and through the iield of the motor, the connections being such as to cause the motor to act as a retarder or'resistance while being driven backward during the descent ol the load and to excite the solenoid 1.? in a manner to release or partially release the brake h, the maximum resistance in the electrical circuit being included at the outset, so that there shall be no danger of overheating the motor even if the load does not start at once. The tendency of the load and its effect when moving downward is to revolve the drum (1 and run the motor backward, thus generating counter elrctroinotive force and opposing the current which flows from the line through the resistance 9. Simultaneously the brake is proportionately released through the action of the solenoid, as described, and the combined resistance of the mechanical brake and the retarding efi'ect of the current in the motor being less than the effort of the load to descend. the motor is driven backward at a controlled speed by the load as it descends. As soon as a balance is reached between the stress of the load and the action of the partially-relieved brake, together with the resistance olfered by the motor to rotation backward, the drum d will continue to be rotated backward at a fixed speed by the action of the load. If the movable contact at m be shifted farther, cut ting out a portion of the resistance Q and a portion of the resistance r, the motor will be made stronger, its tendency to resist being drivenbackward by the load will be made greater, and the opposition ollered to being driven backward of the motor under the stress of the load will be increased. Through the cutting out of some of the resistance 'r the brake it will be further relieved and somewhat in proportion to the increase of resist-- ance offered by the motor to the running backward of the drum; but the relief of the brake in practice is greater than the increase or" the current through the motor, so that the speed of descent of the load will increase.

The counter electromotive force generated by the motor being driven backward by the load will increase with its speed, and a balance will eventually be attained, so that the load will continue thereafter to descend at a fixed speed, but at a speed greater than that in the first instance. The shifting of the movable contact at m is continued, if desired, until the whole current passesdi'rect to the solenoid and to the motor, relieving the brake 7b entirely and leaving to the motor the whole effort to resist the descent of the load.

eansvo Instead ofleading the line Z to "the center of motion of the movable contact at m it might be connected to a lined contact, as at m, the circuit being completed by the movable contact sweeping over such fixed contact and the resistance-terminals. Furthermore, as the load which is lowered is usually much less than the load which is raised the lield of the motor may be divided, if desired, as shown in Fig. 3, a portion only of such "held, as 0 being in connection with the re sistance q for lowering, While the whole field 0 0 may be in connection with theresistance 1. or raising the load. i

In the embodiment of the invention herein illustrated the motor is represented as a di rect-current motor of ordinary type; but it will be understood that any suitable motor which can be made to offer resistance to backward rotation can be employed, as well as that variousotherchanges in details of construction and arrangement can be made-to suit different conditions of use, and that the invention is not restricted to the precise construction and arrangement shown and described herein.

I claim as my invention 1. In an electric hoisting apparatus, the combination of a motor, a hoisting-drum, a mechanical brake, means to decrease the resistance of the mechanical brake, and means to increase the resistance of the motor to backward rotation.

2. In an electric hoisting apparatus, the combination of amotor, a hoisting-drum, a mechanical brake", meansto. progressively decrease the resistance of the mechanical brake, and means to progressively increase the resistance of the motor to backward rotation.

3. In an electric hoisting apparatus, the combination of a motor, a hoisting-drum, a mechanical brake for said drum, means to decrease progressively the resistance of said brake and permit the load to descend, and

means acting to cause said motor to operate with progressive force as a progressive resistance to the descent of the load when running backward during, the descent of the load.

4. In an electric hoisting apparatus, the combination of a motor, a hoisting-drum, a friction-brake for said drum, electromagnetic devices to control said brake, means to actuate said devices to release the brake progressively and means acting to cause said motor to operate with progressive force as a resistance to the descent of the load when running backward during the descent of the load.

5. In an electric hoistin apparatus, the combination of a motor, a oisting-drum, a mechanical brake, means to decrease the resistance of the mechanical brake progressively, variable resistances included in the field-circuit oi the motor, and .Ineans.wherev by the circuit is closed through said resistances to increase the resistanc of the motor to backward rotation as the brake is progressively released.

6. In an electric hoisting apparatus, the combination of a motor, a hoisting-drum, an

electrically-controlled mechanical brake for said drum, variable resistances included'respectively in the fieldcircuit of the motor and in the circuit of said electrical controlling devices, and means whereby the circuit is closed through said resistances to release the' brake and to cause the motor to operate as a resistance to the descent of the load when running backward during the descent of the load, the respective resistances be'ing progressively reduced.

7. In an electric hoistin apparatus, the combination of a motor, a oistingdrum, a mechanicalabrake, means to decrease the resistance of the mechanical brake, electrical connections for driving said motor in hoisting and electrical connections for increasing the resistance of the motor to backward rotation during the descent of the load, the whole of the field of the motor being included in the connections for hoisting and a portion only of the field of the motor bein included in the connections for increasing t e resistance of the motor to backward rotation.

8. In an electric hoistin combination of a motor, a lioisting drurn, a mechanical brake for said drum, means to release said brake'and" permit the load to de scend, electrical connections for driving said motor in hoisting, electrical connections for increasin the resistance of the motor, to I backward rotation and variable resistances included in the field-circuit of the motor, the whole of the field ofthe motor being included in the connections for hoisting and a portion apparatus, the

only of the field of the motor being included in the connections to increase the resistance of the motor to backward rotation.

9. In an electric hoistin apparatus, the combination of a motor, a oisting-drum, a mechanical brake for said drum, electromag- ,netic devices for controlling said brake, electrical connections whereby said devices are actuated to release the brake, electrical connections for driving said motor in hoisting, .and electrical connections for increasing the resistance of-the motor to backward rotation, the whole of the field of the motor being included in the connections for hoisting and a portion only'of the field of the motor being included in the connections for increasing. the resistance of the motor to backward rotation. 1 1,0. In an electric hoistin apparatus, the combination of a motor, a hoistingadrum, a mechanical brake for said drum, electromagnetic devices for controlling said brake, electrical connections whereby said devices are actuated to release the brake, electrical connections for driving said motor in hoisting, and electrical connections for causing said .motor to operate as a generator when running backward duri the descent of the load,

the whole of the fiel of the motor being included in the connections for hoisting and a portion only of the field of the motor 'being included in the connections to cause the motor to operateaas a resistance when running backward.

This application si ned and witnessed this 13th day of July, A 1906.

(JIIAIRLES VVALIJACE HUNT In presence of- Gno. K. JENcKEs, L. D.-GORMAN. 

